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[opt](csv reader) optimize stream load CSV read performance #60920

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66 changes: 54 additions & 12 deletions be/src/vec/exec/format/csv/csv_reader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@
#include "vec/core/block.h"
#include "vec/core/column_with_type_and_name.h"
#include "vec/data_types/data_type_factory.hpp"
#include "vec/data_types/serde/data_type_string_serde.h"
#include "vec/exec/format/file_reader/new_plain_binary_line_reader.h"
#include "vec/exec/format/file_reader/new_plain_text_line_reader.h"
#include "vec/exec/scan/scanner.h"
Expand Down Expand Up @@ -355,6 +356,7 @@ Status CsvReader::get_next_block(Block* block, size_t* read_rows, bool* eof) {
block->set_columns(std::move(mutate_columns));
} else {
auto columns = block->mutate_columns();
_nullable_str_col_cache.clear();
while (rows < batch_size && !_line_reader_eof) {
const uint8_t* ptr = nullptr;
size_t size = 0;
Expand Down Expand Up @@ -643,6 +645,32 @@ Status CsvReader::_fill_dest_columns(const Slice& line, Block* block,
std::vector<MutableColumnPtr>& columns, size_t* rows) {
bool is_success = false;

// Initialize cached column pointers on first call per batch to avoid per-row assert_cast.
// Also pre-reserve capacity for offsets/chars/null_map to eliminate realloc during row loop.
if (UNLIKELY(_nullable_str_col_cache.empty())) {
_nullable_str_col_cache.resize(_file_slot_descs.size());
_has_escape_char = (_options.escape_char != 0);
const size_t batch_size = std::max(_state->batch_size(), (int)_MIN_BATCH_SIZE);
for (int i = 0; i < _file_slot_descs.size(); ++i) {
if (_use_nullable_string_opt[i]) {
IColumn* col_ptr =
_is_load
? columns[i].get()
: const_cast<IColumn*>(block->get_by_position(_file_slot_idx_map[i])
.column.get());
auto& null_col = assert_cast<ColumnNullable&>(*col_ptr);
auto* str_col = assert_cast<ColumnStr<uint32_t>*>(&null_col.get_nested_column());
auto* null_map = &null_col.get_null_map_data();
_nullable_str_col_cache[i].nested_str_col = str_col;
_nullable_str_col_cache[i].null_map = null_map;
// Pre-reserve to avoid repeated realloc inside insert_data/push_back.
str_col->get_offsets().reserve(str_col->get_offsets().size() + batch_size);
str_col->get_chars().reserve(str_col->get_chars().size() + batch_size * 64);
null_map->reserve(null_map->size() + batch_size);
}
}
}

RETURN_IF_ERROR(_line_split_to_values(line, &is_success));
if (UNLIKELY(!is_success)) {
// If not success, which means we met an invalid row, filter this row and return.
Expand All @@ -656,20 +684,34 @@ Status CsvReader::_fill_dest_columns(const Slice& line, Block* block,
? _split_values[col_idx]
: Slice(_options.null_format, _options.null_len);

IColumn* col_ptr = columns[i].get();
if (!_is_load) {
// block is a Block*, and get_by_position returns a ColumnPtr,
// which is a const pointer. Therefore, using const_cast is permissible.
col_ptr = const_cast<IColumn*>(
block->get_by_position(_file_slot_idx_map[i]).column.get());
}

if (_use_nullable_string_opt[i]) {
// For load task, we always read "string" from file.
// So serdes[i] here must be DataTypeNullableSerDe, and DataTypeNullableSerDe -> nested_serde must be DataTypeStringSerDe.
// So we use deserialize_nullable_string and stringSerDe to reduce virtual function calls.
RETURN_IF_ERROR(_deserialize_nullable_string(*col_ptr, value));
// Inline fast path: bypass StringSerDe and per-row assert_cast entirely.
auto& cache = _nullable_str_col_cache[i];
if (_empty_field_as_null && value.size == 0) {
cache.nested_str_col->insert_default();
cache.null_map->push_back(1);
continue;
}
if (_options.null_len > 0 &&
!(_options.converted_from_string && value.trim_double_quotes())) {
if (value.compare(Slice(_options.null_format, _options.null_len)) == 0) {
cache.nested_str_col->insert_default();
cache.null_map->push_back(1);
continue;
}
}
if (UNLIKELY(_has_escape_char)) {
escape_string_for_csv(value.data, &value.size, _options.escape_char,
_options.quote_char);
}
cache.nested_str_col->insert_data(value.data, value.size);
cache.null_map->push_back(0);
} else {
IColumn* col_ptr = columns[i].get();
if (!_is_load) {
col_ptr = const_cast<IColumn*>(
block->get_by_position(_file_slot_idx_map[i]).column.get());
}
RETURN_IF_ERROR(_deserialize_one_cell(_serdes[i], *col_ptr, value));
}
}
Expand Down
10 changes: 10 additions & 0 deletions be/src/vec/exec/format/csv/csv_reader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,8 @@
#include "io/file_factory.h"
#include "io/fs/file_reader_writer_fwd.h"
#include "util/slice.h"
#include "vec/columns/column_nullable.h"
#include "vec/columns/column_string.h"
#include "vec/data_types/data_type.h"
#include "vec/exec/format/file_reader/new_plain_text_line_reader.h"
#include "vec/exec/format/generic_reader.h"
Expand Down Expand Up @@ -283,6 +285,14 @@ class CsvReader : public GenericReader {
// save source text which have been splitted.
std::vector<Slice> _split_values;
std::vector<int> _use_nullable_string_opt;

// Cached column pointers for nullable string fast path, avoiding per-row assert_cast.
struct NullableStringColumnCache {
ColumnStr<uint32_t>* nested_str_col = nullptr;
NullMap* null_map = nullptr;
};
std::vector<NullableStringColumnCache> _nullable_str_col_cache;
bool _has_escape_char = false;
};
} // namespace vectorized
#include "common/compile_check_end.h"
Expand Down
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